α-amino-substituted acetic acids or acid salts and their use in cosmetics

ABSTRACT

α-Amino-substituted acetic acids or acid salts of formula ##STR1## where R represents a hydrogen atom or an alkyl or alkoxy group X represents a hydrogen atom, an alkali metal or alkaline-earth metal or an ammonium residue characterized in that they are totally free of haloacetic acid and alkali metal halide. They are capable of being obtained by reaction, under hot conditions, of glyoxal, or of a precursor of glyoxal, with a secondary amine or one of its salts of formula ##STR2## where R represents a hydrogen atom or an alkyl or alkoxy group, optionally followed by hydrolysis. They may be used as amphoteric surface-active agents for the manufacture of cosmetic compositions.

The subject of the present invention is α-amino-substituted acetic acidsor acid salts which are totally free of haloacetic acid and alkali metalhalide, as well as a process for the preparation of the said acids orsalts and the use of the said α-amino substituted acetic acids or acidsalts of very high purity as surface-active agents in cosmeticcompositions.

SUMMARY OF THE INVENTION

According to the invention, they are α-amino-substituted acetic acids oracid salts of formula (I) ##STR3## in which formula R represents ahydrogen atom or a linear or branched and optionally substituted C₁ -C₁₈alkyl or alkoxy group,

X represents a hydrogen atom, an alkali metal or alkaline-earth metal oran ammonium residue characterized in that they are totally free ofhaloacetic acid and alkali metal halide.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is very particularly aimed at the acid form ofN-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine and itssalts.

Numerous compounds of general formula (I) and more particularly theirinorganic salts are widely employed in the detergent and cosmeticsindustries as amphoteric agents. Apart from their surfactant qualities,these compounds also show themselves to have, owing to their chemicalstructure, a very desirable biodegradable nature. By way of aparticularly advantageous compound, there may especially be mentionedthe sodium salt ofN-lauroyl-N'-(2-hydroxyethyl)-N'(carboxymethyl)ethylene-diamine.

These compounds are conventionally prepared from a compound of generalformula (II) ##STR4## which undergoes condensation with chloroaceticacid or with one of its salts.

This synthesis route is, however, not satisfactory for various reasons.

Direct condensation of a chloracetic acid only leads to a poor yield, ofthe order of 33%, and in addition requires a purification step.

As regards more particularly the inorganic salts of chloroacetic acid,they do indeed lead to better yields, but also to the formation of largeamounts of impurities such as, for example, sodium chloride in theparticular case of sodium chloroacetate. It is then necessary to useawkward purification techniques, of the electrodialysis or osmosis typewhich, apart from their cost, have the disadvantage of being difficultto implement industrially.

Finally, like its salts, chloroacetic acid has an irritant nature whichhas now been well established.

For these reasons, it is desirable now to have available compounds offormula (I) which are totally free of haloacetic acid and alkali metalhalide. In addition, the acids or acid salts of the invention preferablydo not contain more than 0.5% of their weight of glycolic acid.

The compounds forming the subject of the invention are capable of beingobtained by reaction, under hot conditions, of glyoxal, or of aprecursor of glyoxal, with a secondary amine or one of its salts ofgeneral formula (II), ##STR5## in which R represents a hydrogen atom ora linear or branched and optionally substituted C₁ -C₁₈ alkyl or alkoxygroup, optionally followed by hydrolysis.

Apart from the fact that such a process precludes the use ofchloroacetic acid or one of its derivatives, it advantageously permits adirect access to the acid form and thus rids itself of the standardinorganic contaminants such as sodium chloride.

The secondary amine of general formula (II) may preferably be obtainedby in situ or extemporaneous basic hydrolysis, in the reaction medium,of an imidazoline of general formula (III) ##STR6## in which formula Rrepresents a hydrogen atom or a linear or branched and optionallysubstituted C₁ -C₁₈ alkyl or alkoxy group.

Hydrolysis of the imidazoline of general formula (III) is effected in aconventional manner in aqueous medium and in the presence of a base. Thebase is more particularly sodium hydroxide. A person skilled in the artis able, owing to his technical competences, to reproduce thishydrolysis.

From the point of view of the operating conditions, this process for thepreparation of the compounds of formula (I) is relatively easy toimplement.

Although the presence of an excess of glyoxal does not affect theprogress of the reaction this compound is preferably used in anequimolar amount relative to the secondary amine. In this way theprocess rids itself of any subsequent purification step.

Precursor of glyoxal is understood to denote any compound which iscapable of generating glyoxal in the reaction medium.4,4',5,5'-tetrahydroxybis 2,2-(1,3-dioxolane)! corresponds in particularto this definition.

The glyoxal used according to the invention preferably takes the form ofaqueous solutions containing 30 to 55% by weight of glyoxal. Of course,other soluble forms of glyoxal prove possible for use according to theinvention.

These various forms are familiar to a person skilled in the art and willtherefore not be redescribed here.

By way of organic solvent capable of being employed according to theinvention there may in particular be mentioned water, alcohols such as,for example, ethanol, methanol and the propanols, as well as theirmixtures. The solvent is more particularly water.

Reaction under hot conditions is understood to denote, according to theinvention, a reaction carried out at a temperature greater than or equalto 60° C.

This is advantageously a temperature between 60° C. and 100° C., andpreferably of the order of 80° C.

The reaction time depends on the temperature. As a guide, a reactioncarried out at 80° C. is finished in approximately 2 to 3 hours.

This process is particularly useful for preparing the acid form ofN-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine. Thiscompound may, for example, be obtained by the condensation reaction,under hot conditions, of glyoxal withN-(2-hydroxyethyl)laurylimidazoline or of 4,4',5,5'-tetrahydroxybis2,2'-(1,3-dioxolane)! with N-lauroyl-N'-(2-hydroxyethyl)ethylenediamine.

The acid form of the compounds of general formula (I) may besubsequently converted to its salts with alkali metals, alkaline-earthmetals or ammonium, by standard neutralization procedures which arefamiliar to a person skilled in the art and which will therefore not beredescribed here.

By way of neutralization agent which is capable of being employed, theremay more specifically be mentioned alkali metal or alkaline-earth metalhydroxides and amines such as aqueous ammonia and triethanolamine.

The compounds of high purity forming the subject of the invention may beused as amphoteric surface-active agents for the manufacture of cosmeticcompositions such as shampoos, cleansing milks, etc.

The examples which follow are presented as a guide and cannot beconsidered as a limit of the scope and spirit of the invention.

EXAMPLE 1

A mixture of N-(2-hydroxyethyl)laurylimidazoline (5 g, 18.7 mmol), water(4.4 g), sodium hydroxide pellets (40 mg) and glyoxal at a concentrationof 40% in water (2.7 g, 18.7 mmol) is heated for 8 hours at 80° C. Atthe end of 8 hours, an assay by capillary electrophoresis indicates ayield of 76% ofN-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine.

EXAMPLE 2

A solution of N-(2-hydroxyethyl)laurylimidazoline (5 g, 18.7 mmol) andsodium hydroxide pellets (40 mg) in water (1.06 g) is heated at 80° C.for 1 hour. A mixture of glyoxal at a concentration of 40% in water (2.7g, 18.7 mmol) and 1-propanol (5 g) is then added and the residualsolution is heated for 6 hours at 80° C. An assay by capillaryelectrophoresis indicates a yield of 85% ofN-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylene-diamine.

Example 3

A mixture of N-(2-hydroxyethyl)lauryl-imidazoline (10 g, 37.3 mmol),water (2 g) and sodium hydroxide pellets (80 mg) is heated for 1 hour at80° C. Glyoxal bis(sodium hydrogen sulphite)monohydrate (10.6 g, 37.3mmol) is then added and the mixture is heated for 6 hours at 80° C. Anassay by capillary electrophoresis indicates a yield of 75% ofN-lauroyl-N'-(2-hydroxy-ethyl)-N'-(carboxymethyl)ethylenediamine.

EXAMPLE 4

A mixture of N-lauroyl-N'-(2-hydroxyethyl)ethylenediamine (2.5 g, 8.74mmol), crystallized 4,4',5,5'-tetrahydroxybis 2,2-(1,3-dioxolane)!(0.612 g, 2.9 mmol) and water (9.5 g) is heated for 6 hours at 80° C. Anassay by capillary electrophoresis indicates a yield of 97% ofN-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine.

EXAMPLE 5

A mixture of N-lauroyl-N'-(2-hydroxyethyl)-ethylenediamine (7.28 g, 25.4mmol), crystallized 4,4',5,5'-tetrahydroxybis 2,2-(1,3-dioxolane)!(1.783 g, 8.5 mmol) and 1-propanol (10 g) is heated for 12 hours at 80°C.

An assay by capillary electrophoresis indicates a yield of 19% ofN-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine.

EXAMPLE 6

A mixture of N-(2-hydroxyethyl)laurylimidazoline (20 g, 74.6 mmol),sodium hydroxide pellets (153 mg,) and water (4.169 g) is heated for 1hour at 80° C. Water (41.4 g) is then added and a solution of glyoxal ata concentration of 21% in water (21 g) is run in in the course of twohours at 80° C. The reaction mixture is then heated for 6 hours at 80°C. An assay by capillary electrophoresis indicates a yield of 97% ofN-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine.

The impurity, foaming power and viscosity-increasing power profilecharacteristics of the amphoteric surface-active agent prepared inExample 6 are as follows.

    ______________________________________    Impurities    ______________________________________    pH (aqueous)                Solids    solution at a                content     NaCl    Glycolate    concentration of                (% by       (% by   (% by    10%)        weight)     weight) weight)    ______________________________________    8.0         30          0       0.5    ______________________________________

Foaming power

The foaming power was determined according to the modified Ross-Milestest (standard AFNOR T-73 404) at room temperature, at a concentrationof 0.1%.

    ______________________________________              Volume of foam (in ml)    ______________________________________              310    ______________________________________

Viscosity-increasing power

This is measured using the following formulation

    ______________________________________    amphoteric surface-active agent prepared (Example 6)                               35%    sodium lauryl ether sulphate containing 3 units of    ethylene oxide (aqueous solution at a concentration    of 28%)    distilled water            57%    ______________________________________

The NaCl concentration varies from 0 to 5%; addition of NaCl increasesthe viscosity of the medium.

    ______________________________________    Solids    Viscosity    (mPa.s.)    content (%)              NaCl 0%      NaCl 3%  NaCl 5%    ______________________________________    30        2            51       2,000    ______________________________________

EXAMPLE 7

Shampoo

N-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxy-methyl)ethylenediamineobtained according to Example 4 is introduced into a shampoo formulationas follows:

    ______________________________________    Components      % active substance                                 % weight    ______________________________________    Sodium lauryl ether                    28.3         36    sulphate    N-Lauroyl-N'-(2-                    50           4    hydroxyethyl-N'-    carboxymethyl)-    ethylenediamine    Cocoamidopropyl betaine                    35           4    Polyquaternium-17            0.5    Coconut diethanolamide       1.5    Sodium benzoate              0.2    Coloring agent               0.1    Citric acid                  qs    Sodium chloride              qs    Perfume                      qs    Distilled water              qs 100    ______________________________________

This shampoo formulation has a pH of 6.4 and a viscosity of 1678 mPa.s.

The use of the acid form ofN-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine makes itpossible to limit considerably the amounts of citric acid required toobtain a pH of 6.4.

EXAMPLE 8

Baby cleansing milk

The compound obtained according to Example 4 is also introduced into ababy cleansing milk formulation. In order to do this, hydroxypropyl guargum is introduced into water with vigorous stirring, and the pH is thenadjusted to 5-6 with citric acid. The guar gum solution is subsequentlyintroduced into the mixture of surfactants andN-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine, and thepH is adjusted to 7 with citric acid.

    ______________________________________                      % of                      active    Components:       material                              % by weight    ______________________________________    N-lauroyl-N'-(2-  50.0    20.0    hydroxyethyl)-N'-    (carboxymethyl)ethyl-    enediamine    Hydroxypropyl guar gum    0.3    trimonium chloride    Bromonitrodioxane 10.0    0.2    Citric acid       30.0    qs    Perfume                   0.2    Coloring agent    1.0     0.1    Distilled water           qs 100    ______________________________________

The pH is of the order of 7.5 and the viscosity is 10 mPa.s.

I claim:
 1. Process for the preparation of α-amino-substituted aceticacids or acid salts of formula (I) ##STR7## in which formula Rrepresents a hydrogen atom or a linear or branched and optionallysubstituted C₁ -C₁₈ alkyl or alkoxy groupX represents a hydrogen atom,an alkali metal or alkaline-earth metal or an ammonium residuecharacterized in that glyoxal or a precursor of glyoxal is reacted bycondensation, at a reaction temperature, with a secondary amine or withone of its salts of general formula (II), ##STR8## in which R representsa hydrogen atom or a linear or branched and optionally substituted C₁-C₁₈ alkyl or alkoxy group, optionally followed by hydrolysis. 2.Process according to claim 1, wherein the amine of general formula (II)is obtained by in situ or extemporaneous basic hydrolysis, in thereaction medium, of an imidazoline of general formula (III) ##STR9## inwhich R represents a hydrogen atom or a linear or branched andoptionally substituted C₁ -C₁₈ alkyl or alkoxy group.
 3. Processaccording to claim 1, wherein the reaction temperature is greater thanor equal to 60° C.
 4. Process according to claim 1, wherein saidreaction temperature is between approximately 60° and 100° C.
 5. Processfor the preparation ofN-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine or itssalts with alkali metals, alkaline-earth metals or ammonium, by thecondensation reaction, under hot conditions, of glyoxal withN-(2-hydroxyethyl)laurylimidazoline or 4,4',5,5'-tetrahydroxybis2,2-(1,3-dioxolane)! with N-lauroyl-N'-(2-hydroxyethyl)ethylenediamine.6. Process according to claim 1, wherein glyoxal or the precursor ofglyoxal and the secondary amine are placed together in a molar ratioequal to
 1. 7. Process according to claim 5, wherein the reaction iscarried out in the presence of water. 8.N-Lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine or itssalts with alkali metals, alkaline-earth metals or ammonium, which arecapable of being obtained by the condensation reaction, at a reactiontemperature, of glyoxal with N-(2-hydroxyethyl)laurylimidazoline or4,4',5,5'-tetrahydroxybis 2,2-(1,3-dioxolane)! withN-lauroyl-N'-(2-hydroxyethyl)ethylenediamine.
 9. N-Lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine or its salts withalkali metals, alkaline-earth metals or ammonium, according to claim 8,the reactants are brought together in a molar ratio equal to
 1. 10.N-Lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine or itssalts with alkali metals, alkaline-earth metals or ammonium, accordingto claim 8, wherein the reaction temperature is greater than or equal to60° C. 11.N-Lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine or itssalts with alkali metals, alkaline-earth metals or ammonium, accordingto claim 8, wherein said reaction temperature is between approximately60° C. and 100° C.
 12. N-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine or its salts with alkali metals, alkaline-earth metalsor ammonium, according to claim 8, wherein the condensation reaction iscarried out in the presence of water.
 13. α-Amino-substituted aceticacids or acid salts of formula (I) ##STR10## in which formula Rrepresents a hydrogen atom or a linear or branched and optionallysubstituted C₁ -C₁₈ alkyl or alkoxy group,X represents a hydrogen atom,an alkali metal or alkaline-earth metal or an ammonium residue which aretotally free of haloacetic acid and alkali metal halide. 14.α-Amino-substituted acetic acids or acid salts according to claim 13,which they contain no more than 0.5% of their weight of glycolic acid.15. A cosmetic composition comprising an amphoteric surface active agentcomprising the α-amino-substituted acetic acids or acid salts accordingto claim
 13. 16.N-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine or itssalts with alkali metals, alkaline-earth metals or ammonium, which aretotally free of haloacetic acid and alkali metal halide. 17.N-lauroyl-N'-(2-hydroxyethyl)-N'-(carboxymethyl)ethylenediamine or itssalts with alkali metals, alkaline-earth metals or ammonium, accordingto claim 3, which contains glycolic acid in an amount between 0% and0.5% by weight.
 18. α-Amino-substituted acetic acids or acid salts offormula (I) ##STR11## in which formula R represents a hydrogen atom or alinear or branched and optionally substituted C₁ -C₁₈ alkyl or alkoxygroup,X represents a hydrogen atom, an alkali metal or alkaline-earthmetal or an ammonium residue, which acids or salts are totally free ofhaloacetic acid and alkali metal halides and are capable of beingobtained by reaction, at a reaction temperature, of glyoxal or of aprecursor of glyoxal, with a secondary amine or one of its salts offormula (I), ##STR12## in which R represents a hydrogen atom or a linearor branched and optionally substituted C₁ -C₁₈ alkyl or alkoxy group,optionally followed by hydrolysis.
 19. Acids or acid salts according toclaim 18, wherein the amine of formula (II) is obtained by in situ orextemporaneous basic hydrolysis, in the reaction medium, of animidazoline of formula (III) ##STR13## in which R represents a hydrogenatom or a linear or branched and optionally substituted C₁ -C₁₈ alkyl oralkoxy group.
 20. Acids or acid salts according to claim 18, whereinglyoxal or the precursor of glyoxal and the secondary amine are broughttogether in a molar ratio equal to
 1. 21. Acids or acid salts accordingto claim 18, wherein said reaction temperature is greater than or equalto 60° C.
 22. Acids or acid salts according to claim 21, wherein thereaction temperature is between approximately 60° and 100° C.
 23. Acidsor acid salts according to claim 18, wherein the reaction is carried outin the presence of water.